1. Field of the Invention
The present invention relates to optical touch display systems and methods, and more particularly to a multi-touch optical touch display system and related method that recognizes ghost points.
2. Description of the Prior Art
Current touch display technology is utilized in many types of electronic products, including automatic teller machines, handheld electronic devices, and displays. Touch display technology can be subdivided into resistive, capacitive, and optical touch. Resistive and capacitive touch display technologies utilize electric field variations on a touch display surface caused by an object contacting a sensor device to position the object. Optical touch display technologies utilize optical path blockages or optical image variations caused by an object moving on a surface of a touch display to position the object.
Optical touch display technology does not require special fabrication and components in display device manufacturing processes, so optical touch display manufacturing costs are typically lower than those of resistive or capacitive touch screens. However, optical touch displays are susceptible to detection errors when utilized in multitouch configurations, due to intersection points formed by blocking of multiple optical paths. Although the prior art may utilize images captured at different instants to determine true touch points, if an object being detected is static, the true touch points cannot be determined. Please refer to FIG. 1, which is a diagram illustrating ghost points formed in an optical touch display performing multitouch detection due to blocking of multiple optical paths. As shown in FIG. 1, optical paths of light emitted by light sources 101, 102 are blocked by objects O1, O2 being detected. Because the optical touch display of the prior art is only able to detect whether or not an optical path is blocked (and cannot determine distance to the object), the optical touch display not only finds the objects O1, O2, but also generates ghost points G1, G2 due to intersection points of the blocked optical paths.